The presented pie charts demonstrate the key sources of energy utilized in the United States. In fact, the figures are given in the period of the 1980s and 1990s.
As a whole, oil can be considered as the main source used in both time periods. On the other spectrum, hydroelectric power was the least utilized medium as per the circle graph.
At the first glance, oil contributed to the majority of the production at 42% in 1980, whereas, a 9% decrease was witnessed in the succeeding year. In contrary, the hydroelectricity only occupied 5% of each chart.
Coal is the most prominent source in the nineties after oil, which is just above a quarter in 1980, and approximately just below a third. In terms of natural gas, which is 26% and 25%, respectively. Lastly, nuclear energy was employed to obtain 5% in the eighties, while the amount doubled during the nineties.